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From BioCycle Journal of Composting &Organics Recycling August 2001, Page 43 |
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SEPARATING FOOD RESIDUALS
TESTING FEASIBILITY OF HOUSEHOLD FOOD RESIDUALS DIVERSION
The city of Seattle evaluates biweekly collection methods for household separated food residuals and yard trimmings.
Jennifer Bagby and Tanya Tarnecki
SEATTLE officials are asking what additional steps they can take to reduce residential waste in a community where residents already source separate much of their recyclable paper, plastic and metal. For single family residences in Seattle, the largest portion of waste not already addressed by recycling programs is compostable food, representing about 31 percent. Add the estimated seven percent of household garbage that is compostable paper, and it appears that as much as 38 percent of the remaining single family waste stream could be targeted for diversion.
Previous pilot studies had indicated that Seattle residents were willing to participate in a weekly food residuals collection program. However, a weekly program would add significantly to the cost of municipal diversion programs. Since the main driver of program costs is frequency of collection, the city hired Cascadia Consulting Group to find out if a biweekly collection program was feasible.
In a pilot project conducted last summer and autumn, Cascadia recruited approximately 425 single family households to test the feasibility of adding food residuals to existing biweekly yard trimmings collection. Unlike previous pilot efforts, this arrangement eliminated the need to reconfigure existing trucks or add a separate fleet of trucks to collect food residuals. Through the pilot, the city sought to gauge household acceptance, note any needed modifications of collection and transfer systems and gain information necessary for Health Department approval of a program to collect food residuals biweekly.
PROJECT DESIGN
In the primary phase of the pilot project, residents of 425 single family dwellings in two test neighborhoods were asked to separate food residuals and compostable paper from the rest of their garbage. Each household received a 22-gallon mini can from the city along with a detailed information sheet describing types of materials to place in the can. Residents also were encouraged to place some yard trimmings in layers within the food residuals to minimize odor and seepage. The contents of the minican were collected biweekly between July 20 and October 12, 2000.
The follow-up phase of the pilot project was developed after the city learned of organic collection programs in eastern Canada that use a specially designed 96-gallon aerated container to collect food and compostable paper along with larger volumes of yard trimmings. In order to test residents’ acceptance and the ease of collection with the larger container, 50 additional households were recruited in early autumn. Recipients of the larger containers, manufactured by Cascade Carts, were instructed to use them for all of their yard trimmings, as well as for compostable food and paper.
In both the primary and follow-up studies, the contracted garbage haulers collected the materials in conjunction with biweekly yard trimmings pick ups in their neighborhoods. (Table 1 summarizes the two programs.) Collected materials were taken to Cedar Grove’s composting facility in Maple Valley, Washington, where the city’s yard trimmings are processed. During each collection, field staff observed the process and recorded the incidence of odors, insects, rodents, leachate and other concerns. When each study phase was completed, participants were contacted by telephone and asked to indicate their level of satisfaction with the collection method.
OBSERVATIONS MADE AT THE CURBSIDE
The observations made by field staff during each round of collection suggested relatively few problems with the accumulation of food residuals or mixed yard trimmings and food in outdoor containers.
Participation: Initially, 26 percent of the 425 residents participated in the primary study, but involvement declined slightly over time. Overall, 20 to 25 percent participated in any given week. In contrast, during the 96-gallon container trial, 45 percent of residents participated in the first collection, and involvement remained relatively stable over time (Figure 1).
These participation levels were encouraging, since relatively little effort had been made to persuade residents to separate their food residuals. Prior to distribution of the containers, the only communication with residents had been a brief mailer asking them to participate and describing the benefits and ease of food residuals separation.
Residents were more likely to fill the containers when asked to include all of their yard trimmings. The 22-gallon minicans used in the primary study were seldom full. Over the seven collections, nearly half of the food residuals bins collected were less than 25 percent full. However, the 96-gallon containers used in the followup study were generally much more full and, as expected, contained a larger percentage of yard trimmings.
Contaminants: In both container trials, plastics and other contaminants were infrequent. Only a few residents included unacceptable materials such as plastic bags or Styrofoam.
Odors: Only about one-fifth of all setouts during the primary study emitted even a mild odor. During warm weeks, however, the incidence of odors, which was observed with the lid on the container, reached as high as 67 percent. Still, bin odors in the primary study were almost never rated severe. Odor was even less common with 96-gallon containers, which were equipped with aeration holes in the sides. With the large container, there were no severe odor incidents and only two percent of the large containers gave off even a mild odor. Anecdotal comments from the field staff suggested that few odor problems occurred even when the lid was open on the large container, although cooler weather during the large container trial was a likely factor.
Vectors: Most minicans attracted insects in the primary study. Approximately two-thirds of containers set out for collection had insects inside, while about one-third had insects around the bin. Over time, the percentage of bins with insects inside the container closely correlated with the average daily temperature for the two-week collection period. Insects were less prevalent in the large containers, with one-fifth of setouts having insects in the container and only a single one having insects nearby. Rodent problems were not apparent within either type of container, and in only a few cases was there evidence that rodents had been near the outside of the containers.
PARTICIPANTS’ REACTIONS TO THE PROJECT
After each container trial, a phone survey was conducted to yield additional information on residents’ perceptions and attitudes about food residuals composting. Although the majority of survey responses came from residents who received the minicans, there were enough responses from recipients of the 96-gallon containers to make rough comparisons.
A feeling of obligation made some residents participate, while a fear of mess discouraged others from trying it. Survey respondents most often reported that composting makes sense and feelings of obligation were their main reasons for participating. Some residents also said they were interested in reducing waste. The perception that the collection process would be too messy and smelly was the most common reason that survey respondents gave for not participating or why they tried participating but did not take part in all collections. Some respondents reportedly did not take part because they already compost their food residuals or did not generate enough to make participation worthwhile. Complaints about mess and smell were notably less frequent in the phone survey of residents using the large aerated container.
Most participants liked reducing their household waste and composting, instead of disposing, their food residuals. These were the top two "likes" that participants reported about the pilot program. The most commonly cited dislike in the primary study was that the process was too messy and smelly, but this response was rare for participants who used the aerated container.
More than half of participants reported they had no problems with the process. Of the problems reported, "messy/smelly" was the most common. Participants also noted problems with fruit flies, and some reported the process took too much time. Among survey respondents who participated in the study, the majority — 77 percent — indicated they were "somewhat likely" or "very likely" to participate in a future biweekly food residuals collection program (Figure 2). Reported likelihood of future participation was even higher for recipients of the large food/yard trimmings containers. Additionally, some respondents said that increasing or changing the collection frequency, to weekly instead of biweekly for example, could increase their likelihood of participating in the future.
Of the households that participated in the study, about 35 percent indicated that they would be willing to pay $2/month for the service. Willingness to pay was twice as likely in the study neighborhood in northern Seattle, where the households had higher median incomes.
LESSONS LEARNED
In short, biweekly collection of food residuals can work. As the results of the follow-up study indicated, the keys to successful collection of organics include using a large aerated container and requesting residents to mix food, compostable paper and yard trimmings together. In addition, public education will be crucial to encourage participation and to counter the perception and reality that the process is "smelly and messy." This can be accomplished by teaching participants to use compostable paper and yard trimmings to reduce odors, insects and mess. A strong educational program also may serve to increase participation by reinforcing the benefits of waste reduction and instilling a sense of duty to compost.
Now, Seattle officials must decide if a residential food residuals program will be the next step in Seattle’s quest for higher diversion. The city has a 60 percent residential recycling goal. The biggest motivator for expanded organics recovery is to essentially divert about 30 percent of the disposal stream. In addition, the city’s variable rate program for garbage collection would provide a strong incentive for residents to produce smaller amounts of waste for curbside collection.
Jennifer Bagby is Principal Economist with Seattle Public Utilities. Tanya Tarnecki is an Associate of Cascadia Consulting Group. Copies of the full report of the pilot project and additional information about Seattle’s programs can be found at http://www.ci.seattle.wa.us/util/solidwaste.
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